assignment in select

with new select operator

R=r
OCL=15418
CL=15418

src/cmd/gc/go.h

@@ -702,6 +702,8 @@ Node*	reorder4(Node*);
 Node*	structlit(Node*);
 Node*	arraylit(Node*);
 Node*	maplit(Node*);
+Node*	selectas(Node*, Node*);
+Node*	old2new(Node*, Type*);
 
 /*
  *	const.c

src/cmd/gc/go.y

@@ -427,7 +427,7 @@ complex_stmt:
 		// right will point to next case
 		// done in casebody()
 		poptodcl();
-		$$ = nod(OAS, colas($2, $4), $4);
+		$$ = nod(OAS, selectas($2,$4), $4);
 		$$ = nod(OXCASE, $$, N);
 	}
 |	LDEFAULT ':'

src/cmd/gc/walk.c

@@ -1232,6 +1232,30 @@ out:
 	return r;
 }
 
+Node*
+selectas(Node *name, Node *expr)
+{
+	Node *a;
+	Type *t;
+
+	if(expr == N || expr->op != ORECV)
+		goto bad;
+	t = expr->left->type;
+	if(t == T)
+		goto bad;
+	if(isptr[t->etype])
+		t = t->type;
+	if(t == T)
+		goto bad;
+	if(t->etype != TCHAN)
+		goto bad;
+	a = old2new(name, t->type);
+	return a;
+
+bad:
+	return name;
+}
+
 void
 walkselect(Node *sel)
 {
@@ -1270,6 +1294,16 @@ walkselect(Node *sel)
 				yyerror("select cases must be send or recv");
 				break;
 
+			case OAS:
+				// convert new syntax (a=recv(chan)) to (recv(a,chan))
+				if(n->left->right == N || n->left->right->op != ORECV) {
+					yyerror("select cases must be send or recv");
+					break;
+				}
+				n->left->right->right = n->left->right->left;
+				n->left->right->left = n->left->left;
+				n->left = n->left->right;
+
 			case OSEND:
 			case ORECV:
 				if(oc != N) {